The Tentative Rise of the British Bottlenose Dolphin

Wrought with anxieties over future food shortages in the decades following the Second World War, British farmers turned to high-yield pesticide-intensive methods. These pollutants of the ‘Insect Apocalypse’ also caused drastic declines in marine mammal populations including fish, otters and dolphins.

A haven for coastal megafauna such as humpback and minke whales, the south-western UK coast has also been home through the years to a tiny pod of bottlenose dolphins which has slowly increased since the 1990s from a couple of sighted individuals to approximately 40 today.

The pod is genetically distinct from outside populations meaning they really are ‘British’. So much so that generations have grown ‘bigger’, ‘rounder’ and ‘stumpier’ for the chilly waters.

Bottlenose dolphins are ‘indicator species’ meaning their growing presence is taken by ecologists as a sign of ecosystem recovery.

‘Like any top marine predator, if it's doing really well then ultimately we as humans should be doing really well.’ Says Abigail Crosby, Marine Conservation Officer at Cornwall Wildlife Trust (CWT). ‘It shows that the state of our seas is good.’

Cetaceans are identified by their fins. Whereas humpbacks are identified by their iconic tail flukes, bottlenoses are identified by the notches and marks on their dorsal fins. Three individuals are known as ‘Topless’, ‘Scratchy’ and ‘Overhang’.

Local groups are vital to the ongoing monitoring and CWT’s Your Shore Network has seventeen community initiatives. ‘Citizen science is really important for such a mobile elusive species.’ Said Crosby. Support from citizens grew during the pandemic as people made efforts to rediscover nature.?

The Marine Strandings Network also forms a core part of data collection. Though somewhat macabre, washed-up carcasses provide vital biological insights and evidence of life events such as age, cause of death and the potential presence of infectious diseases such as Brucella which can be transferred to humans (in rare cases). The ‘non-invasive’ approach investigates an annual average of 250 individuals.?

Cornwall has such abundance that CWT accounts for approximately 20% of strandings data on DEFRA’s national species database. The major threat accounting for 30% of dolphin deaths is bycatch where species are accidentally caught in fishing equipment such as nets.?

Tales of dolphins go back millennia in Britain. Roman historian and naturalist Pliny the Elder described walking on a coastal path one day when he saw a boy being carried to school across an inlet by a dolphin.

‘[The dolphin] does not dread man, as though a stranger to him, but comes to meet ships, leaps and bounds to and fro, vies with them in swiftness, and passes them even when in full sail.’ Pliny, 77BC, Naturae Historiae.

Small bottlenose populations exist also in Moray Firth, Scotland and Cardigan Bay in Wales.

?If you would like to hear our special podcast on this story you can view or listen from the links below:

Restore Our Planet Podcast: #22 Britain's Returning Bottlenose Dolphins: Abby Crosby (RSS & Spotify)

Restore Our Planet Podcast #22 (Youtube)

Sources

‘CHAP. 8.—Human Beings Who Have Been Beloved By Dolphins. ’

‘Pesticides, pollution and the UK's silent spring, 1963–1964: Poison in the Garden of England ’

‘Wildlife Matters LIVE - Cornwall’s Bottlenose dolphins ’